<!DOCTYPE HTML>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <title>取消计时器</title>
    <script type="text/javascript">
        function clock() {
            var time = new Date();
            document.getElementById("clock").value = time;
        }

        // 每隔100毫秒调用clock函数，并将返回值赋值给i
        var i = setInterval("clock()", 100);
    </script>
</head>
<body>
<form>
    <input type="text" id="clock" size="50"/>
    <input type="button" value="Stop" onclick="clearInterval(i)"/>
</form>
</body>
</html>